You Do Need power plug adapter while traveling from Lebanon to Namibia.

Here is Why You Need An Adapter

The outlet and plug type used in Namibia are D and M and in Lebanon are C, D and G. This is how they look like.

Lebanon

In Lebanon, outlets of type C, D and G are in use.

Type C

Type D

Type G

Namibia

In Namibia, outlets of type D and M are in use.

Type D

Type M